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There are major differences in the metabolism of morphine and the illegal drug heroin. Morphine mostly produces its CNS effects through m-receptors, and at k- and d-receptors. Heroin has a slight affinity for opiate receptors. Most of its actions are due to metabolism to active metabolites (6-acetylmorphine, morphine, and morphine-6-glucuronide).
Bacteria have been found alive in a lake buried one half mile under ice in Antarctica.
Most fungi that pathogenically affect humans live in soil. If a person is not healthy, has an open wound, or is immunocompromised, a fungal infection can be very aggressive.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
The familiar sounds of your heart are made by the heart's valves as they open and close.